Foods containing eggs

Transcription

1 Eggs Chapter 11

2 Foods containing eggs

3 Eggs types Chicken eggs Standard Fertile Free-range Organic Non-chicken eggs Duck Goose Ostrich Quail Turkey

4 Value-added eggs Health of Consumer Special Attributes Nutrient Content of Feed Conditions Under Which Hens Raised Lower-Cholesterol Eggs Omega-3 Fatty Acids Vitamin E Levels Animal Friendly Practices

5 Eggs parts Yolk Germinal Disc Vitelline Membrane Egg White Albumen Chalaza pl. Chalazae Shell Membranes Inner Outer Air Cell Shell Cuticle or Bloom Between 2 Shell Membranes

6 Eggs Components Chalaza pl. Chalazae Ropy Twisted Strands Of Albumen Anchor Yolk to Center of Thick Egg White Vitelline Membrane Membrane Surrounding Egg Yolk Attached to Chalazae Cuticle or Bloom Waxy Coating on Eggshell Protects Against Bacterial Contamination & Moisture Loss

7 EGGS

8 Egg parts Shell: 9-12% of total egg weight. Made of calcium carbonate and magnesium carbonate deposited on protein network. Egg whites or albumen: about 60% of total egg weight. Contains over 40 proteins. Yolk: 30-33% of total egg weight. The only egg part containing fat and cholesterol.

9 Chemical (proximate) composition of egg components Water [%] Protein [%] Lipid [%] Component Carbohydrates [%] Ash [%] Albumen Yolk Whole egg

10 Eggs micronutrients Vitamins Fat-Soluble A D E K B 2 B 12 Folate Biotin Pantothenic Acid Minerals Selenium Iodine Zinc Iron Copper Iron Not Bioavailable Iron & Sulfur React in Overcooked Eggs > Strong Off-Odor

11 Egg safety Remember -egg may cause illness known as salmonellosis. This may result from contamination on the outside of the shell as well as infection inside the egg itself. Any egg that is cracked when purchased or that cracked during preparation should be discarded. Eggs should not be stored at room temperature for more than two hours. Hard cooked eggs should be kept cool until serving

12 Egg safety Separating the yolk from albumen after the shell is broken in half by passing it back and forth between the halves should be avoided. Eggs should be thoroughly cooked for those at risk for infections: the elderly, infants, young children or the ill.

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14 Uses of eggs in food preparation Binding and coating Leavening Emulsifying agent Interfering agent Clarifying agent

15 Changes in the egg quality Occurs as soon as egg is laid Are affected by the conditions the egg is held. First change - loss of weight Formation of the air cell on blunt side of egg - due to contraction of egg content. Egg becomes more alkaline due to loss of carbon dioxide. ph of albumen rises from 7.6 to ph of yolk rises from to 6.8

16 Eggs storage Size of An Egg s Air Cell Provides Another Indication of Its Age

17 Grading of eggs involves assessment of interior and exterior quality condition of albumen and yolk size of air cell soundness of egg shell weight cleanness of egg

18 Eggs grading Haugh Units Freshness of An Egg Detected By Cracking It Open Onto A Flat Surface & Looking At Height of Thick Albumen Fresh Egg Whites Sit Up Tall & Firm Older Ones - Spread Out

19 Egg Sizes by weight

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22 Egg Candling

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24 Proteins Ovalbumin - 54%; globular protein that readily denatures. Ovotransferrin (Conalbumin) - 12%; it forms complexes with iron. The most heat sensitive if not bound to metal ion. Ovomucoid - 11%; resistant to heat denaturation; trypsin inhibitor. Lysozyme - 3.4%; enzyme that hydrolyses polysaccharides present in the cell wall of certain bacteria. Avidin - 0.5%; it forms complex with biotin. Vitamin antagonist. Biotin deficiency is produced after consumption of 24 raw eggs per day. Vitellin and lipovitellins - proteins found in yolk -excellent emulsifying agents.

25 Egg proteins cont.

26 Coagulation of egg proteins Albumen: coagulation starts at 62 C, mass fully coagulates at 65 C. At 70 C coagulum is firm. Yolk: coagulation starts at 65 C; mass fully coagulates at 70 C. Beaten eggs coagulate at slightly higher temperature ~ 69 C.

27 Thickening/coagulation of egg mixture depends on: Rate of heating - egg proteins tend to curdle when heated too quickly. Heating time and heating past coagulation - causes albumen protein to lose water, shrink and toughen, while egg yolk becomesmore crumbly due to fat content. Addition of sugar -elevates the coagulation temperature and produces more tender coagulum. Addition of salt - lowers the coagulation temperature Addition of acid - lowers the coagulation temperature - too much acid will curdle the proteins. Addition of starch - the coagulation temperature of egg proteins and gelatinization temperature of starch are different. Best results are obtained by adding uncooked egg to gelatinized starch. Addition of water - elevates the coagulation temperature.

28 Eggs preparation Microwaving Eggs Cook Extremely Rapidly Special Caution Taken to Avoid Overcooking Manufacturer s Instructions Should Be Followed for Microwave Egg Cooking Whole Eggs w/ Intact Shells Never Microwaved!! Steam Expanding Within Shell Can Cause Eggs to Burst Same Principle Applies to Whole Eggs Out of the Shell Puncture Egg Yolks w/ Toothpick or Tip of a Knife Prior to Microwaving

29 Eggs preparation Custards Ingredients Milk &/or Cream Sweeteners Sugar Honey Flavorings Vanilla Nutmeg Etc. Eggs or Egg Yolks Sweet or Savory Preparation Stirred or Baked Sweet Custards Puddings or As Fillings Savory Custards Nonsweet Quiches Stirred Custard Soft Custard or Custard Sauce Ingredients Stirred While Heated Baked Custard Poured Into Ungreased Custard Cups Placed In The Oven

30 Eggs storage Restaurants Food Service Institutions Other Food Manufacturers Must Be Especially Careful About Storing Eggs Because Large Quantities are Purchased Storage Eggs Used w/i 1 Mo Stored Up to 6 Mos. Eggs Treated w/ A Light Coat of Oil or Plastic Stored In High Humidity At Low Refrigerator Temperatures Very Close to Egg s Freezing Point F C

31 Preservation of eggs REFRIGERATION: Storage under modified atmosphere (humidity, carbon dioxide) Dipping in mineral oil Thermostabilization - dipping for a short time in hot liquid.

32 Eggs preservation Freezing Cannot Freeze Whole Egg It Will Crack Under the Expanding Liquids Food Manufacturers Break the Eggs Open At the Processing Plants Where Contents Are Frozen Whole Separated Whites & Yolk Mixed As Whites or Yolks

33 Preservation of eggs FREEZING cont. : Albumen can be frozen without addition of any protectants. Yolk -without addition of protectant will form irreversible gel. Therefore glycerin, salt or sugar are added to prevent gelation Cooked eggs can be frozen by any method.

34 Preservation of eggs by drying Egg can be dried by spray drying. Free flowing of powder is achieved by addition of silicoaluminum or silicone dioxide. Glucose present in egg affect lower solubility, affect the flavor and color (Maillard reaction) Glucose is removed by oxidation to glucuronic acid in the presence of glucose oxidase. Hydrogen peroxide formed in this reaction is removed by catalase.

35 Preservation of eggs by drying Dried Drying Eggs Is a Simple Process Whole Eggs or Separated Yolks Are Spray-Dried Create a Fine Powder Which Is Mixed w/ Anti-Caking Substances to Prevent Clumping Egg Whites Granule, Flake, or Milled Textures Stored Up to 1 Year In Refrigerator Kept In Tightly Closed Containers to Prevent Clumping That Can Result from Moisture Accumulation

36 Food foams Foam is a gas (air) dispersed in liquid. Foam is stabilized by surface acting agent referred to as foaming agent (example protein that forms a film coat arround air bubble. Hydrophobic groups are directed towards air, while hydrophilic towards water. Egg foams (meringues, angel cakes, sponge cakes, souffles, fluffy omelets) Milk foams

37 Egg foams Factors Affecting Foaming Beating Technique Start Slow Gradually Increasing Speed Testing for Doneness Observe Peak Formation Avoid Overwhipping Prevent Collapse & Separation of Foam Temperature Bowl Beaters Eggs Room Temperature

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39 EGGS FUNCTIONS

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41 Quality of egg foam is affected by: Sugar Acids Salt Fat Temperature Equipment used

42 Egg foams Factors Affecting Foaming Bowl Deep Bowl Rounded Bottom Sloping Sides Avoid Plastic Bowls Separation of Eggs Egg Yolk Contains Fat Interferes w/ Foam Egg Separators Careful Separation of Egg White from Yolk Imperative Do Not Pass Egg Back & Forth Between Two Shell Halves

43 Egg substitutes Better n Egg Egg Beaters Scramblers Second Nature Simply Eggs

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